1. Field of the Invention:
This invention relates to motor operated mechanical drive mechanisms with particular reference to apparatus having utility in precision measuring and/or testing instruments.
2. Discussion of the Prior Art:
Instrument drive mechanisms employing lead screws driven with stepping motors have been seriously restricted in use. When employing standard pitch screws, for example, these mechanisms become limited to applications where total excursions of travel of objects driven thereby were required to correspond precisely to the amount of travel produced by exact multiples of motor pulses. When, on the other hand, it is elected to employ a lead screw of non-standard pitch, the mechanism becomes restricted in use to situations where the total travel required to be produced by the drive mechanism corresponds exactly to the product of the particular screw pitch and number of screw revolutions resulting from selected multiples of full motor pulses.
Accordingly, prior art stepping motor drive mechanisms have very limited application and it is an object of this invention to provide a stepping motor drive mechanism which is uniquely universally adjustable and adaptable to various requirements of object movement and precision positioning or measurements of movement, all or each of which would otherwise require less than a full motor step for completion and ordinarily run short or over desired excursions of travel and/or stopping points.
More particularly, it is an object of invention to provide a mechanism for accomplishing various selected excursions of travel of an object and/or measurements of such travel or precision positioning of the object, each with completion of a full motor step or multiples of full motor steps, i.e. to render a single drive mechanism universally adjustable to various uses.
Still another object is to accomplish the above with incorporation of a standard pitch lead screw.
Other objects and advantages of the invention will become apparent from the following description.